共查询到18条相似文献,搜索用时 218 毫秒
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详细比较了磷酸二氢钾(KDP)晶体的自发拉曼散射和受激拉曼散射光谱,在受激拉曼散射(SRS)中观察到了自发拉曼散射中最强的振动模的三阶Stokes光(559.43,589.74,623.50nm),由于其他振动模的受激拉曼散射增益系数较小,其SRS光谱未观察到。另外,比较了传统生长的未退火和退火后的KDP晶体及快速生长的锥区和柱区KDP晶体的受激拉曼散射增益系数,结果表明生长方法和热退火对KDP晶体的受激拉曼散射增益系数无明显影响。 相似文献
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采用传统降温法从不同程度氘化(x=0, 0.51, 0.85)的生长溶液中生长氘化KH2PO4(KDP) 晶体, 利用正电子湮没技术(正电子寿命谱和多普勒展宽谱)、结合X射线衍射谱(XRD) 结构分析, 对KDP晶体氘化生长的微观缺陷进行了研究, 讨论了氘化程度对晶体内部微观结构特性、缺陷类型和浓度的影响. XRD结果显示晶胞参数a, b值随氘含量的增加而增加, c值无明显变化; 正电子寿命谱结果发现随着氘化浓度的提高, KDP晶体内部中性填隙缺陷以及氧缺陷不断增加, 引起晶体晶格畸变; 氢空位、K空位、杂质替位缺陷不断发生缔合反应形成复合缺陷, 缺陷浓度不断减少; 团簇、微空洞等大尺寸缺陷也在不断发生聚合反应, 缺陷浓度表现为不断减少. 多普勒实验结果表明随着氘化程度的提升, 晶体内部各类缺陷表现为同步变化. 实验结果表明, KDP晶体在低浓度氘化生长(50%以内)下缺陷反应较弱, 而在高浓度氘化(50%以上)下的缺陷反应显著增强. 相似文献
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惯性约束聚变频率转换系统中,大口径薄型KDP晶体的面形质量是影响频率转换效率能否达到设计要求的关键因素之一。针对45放置状态下口径为400 mm400 mm的三倍频KDP晶体,采用ANSYS有限元分析软件,建立了不同夹持方式和具有不同加工误差的KDP晶体模型和夹具模型,分析了加工误差对不同夹持方式下KDP晶体附加面形的影响,给出了不同加工误差和不同夹持情况下,KDP晶体附加面形的P-V值和RMS值。研究结果表明,夹持方式和加工误差是引起KDP晶体附加面形变化的重要因素,正面压条夹持方式即使在晶体和夹具存在加工误差时也可以较好地控制晶体的附加面形。 相似文献
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利用群理论详细分析了磷酸二氢钾(KDP)晶体的拉曼振动模式,得出了其拉曼振动模的归类。并采用拉曼光谱仪测量了Z切退火KDP晶体X(ZZ)珡X,Z(XY)珚Z和Y(XY)X三种散射配置和未退火KDP晶体Z(XY)珚Z配置下的拉曼光谱。根据拉曼选择定则得出X(ZZ)珡X,Z(XY)珚Z和Y(XY)X散射配置下的拉曼峰分别对应A1,B2(LO),B2(TO)对称类振动模,但在Z(XY)珚Z配置下的拉曼光谱中除了B2模,还观察到了A1模,而在Y(XY)X配置下的拉曼光谱中只有B2模,且退火和未退火晶体Z(XY)珚Z配置下的拉曼光谱无明显差别,此结果表明KDP晶体的对称性降低,在背向散射时A1模也具有角度特性,但与晶体的内应力无关,这是由KDP晶体内部结构决定的。 相似文献
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EDXRF determination of impurities in potassium dihydrogenphosphate single crystals and raw materials
《X射线光谱测定》2006,35(2):112-115
A fast and simple preconcentration procedure for recovering various cation impurities from potassium dihydrogenphosphate (KDP) single crystals and raw materials, followed by energy‐dispersive X‐ray fluorescence analysis (EDXRF), is described. The technique is based on the adsorption of metal 8‐hydroxyquinoline complexes from aqueous solutions of KDP on activated carbon, separation of the concentrate on a Nuclepore filter and subsequent determination by EDXRF. To fix activated carbon powder on a filter surface, an amount of 1‐hexadecanol is added to the KDP solution during the preconcentration procedure. The optimum conditions for the best recovery of the impurities were established. It was shown that a preconcentration factor of 100 can be achieved and the detection limit for a number of elements was down to 0.01 µg g?1. The relative standard deviations were 6–17% for element concentrations of 0.2 µg g?1. The method was successfully applied to the determination of Fe, Co, Cu, Ni, Zn, Mn, Ti and Bi in KDP single crystals and raw materials. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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The effect of organic dyes on the dielectric properties of KH2PO4 (KDP) crystals is studied over a wide range of temperatures. The dielectric properties of KDP crystals doped with molecules of the Chicago Sky Blue and Amaranth organic dyes are investigated for the first time. The dye molecules can be incorporated into the crystal lattice of KDP and selectively paint the pyramidal growth sectors of the crystal. The influence of dye organic impurities on the domain contribution to the permittivity is analyzed with due regard for the sectoral crystal structure. It is demonstrated that, upon doping of KDP crystals with organic dyes, the blocking effect of background impurities on domain walls is substantially weakened in the prismatic growth sector of the crystal in the polar phase. This leads to a noticeable change in the dielectric properties, specifically to an increase in the domain contribution to the permittivity of the crystal. 相似文献
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Nonmetallic crystals with high thermal conductivity 总被引:2,自引:0,他引:2
G.A. Slack 《Journal of Physics and Chemistry of Solids》1973,34(2):321-335
Nonmetallic crystals transport heat primarily by phonons at room temperature and below. There are only a few nonmetallic crystals which can be classed as high thermal conductivity solids, in the sense of having a thermal conductivity of > 1 W/cmK at 300K. Thermal conductivity measurements on natural and synthetic diamond, cubic BN, BP and AIN confirm that all of them are high thermal conductivity solids. Studies have been made of the effect on the thermal conductivity of nitrogen impurities in diamond, and oxygen impurities in AIN. The nitrogen impurities scatter phonons mostly from the strain field, the oxygen impurities scatter phonons mostly from the mass defects caused by aluminum vacancies. Pure A1N as well as pure SiC, BeO, BP and BeS conduct heat almost as well as does copper at room temperature, while pure natural and synthetic diamonds conduct heat five times better than copper.All of the nonmetallic solids that are known to possess high thermal conductivity have either the diamond-like, boron carbide, or graphite crystal structure. There are twelve different diamond-like crystals, a few boron carbide-type crystals, and two graphite structure crystals that have high thermal conductivity. Analyses of the rock-salt, fluorite, quartz, corundum and other structures show no candidates for this class. The four rules for finding crystals with high thermal conductivity are that the crystal should have (1) low atomic mass, (2) strong bonding, (3) simple crystal structure, and (4) low anharmonicity. The prime example of such a solid is diamond, which has the highest known thermal conductivity at 300K. 相似文献
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We have studied the Fe-X (X=B, C and N) systems, represented by clusters of atoms, using the discrete variational method.
The calculated properties at the cluster's central site are compared with experimental and other theoretical results. The
local magnetic, contact magnetic hyperfine field and contact charge density at the central site were calculated for different
locations of impurities in bct, fcc and for intermediate structures. The calculated properties for N impurities are somehow
different from those obtained for B and C impurities. The reasons behind the large average magnetic moment at Fe site in Fe-N
systems were not convincingly clarified, however, distinctive features related to these systems are pointed out.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Adriane Chau Morteza Eslamian Nasser Ashgriz 《Particle & Particle Systems Characterization》2008,25(2):183-191
Using spray pyrolysis, solid fully‐filled zirconia particles were synthesized at relatively high reactor temperatures (~ 400 °C) by adding NaCl as impurities to zirconium hydroxychloride (ZHC) precursor that would have lead to the formation of hollow disrupted particles otherwise. FE‐SEM images show that at comparable concentration of NaCl and ZHC both cubic and spherical NaCl/ZrO2 particles form. The particle characteristics were varied by varying solute concentration, type, and solvent content. Addition of NaCl caused the formation of both cubic and spherical particles which were non‐disrupted at even high temperatures. According to the EDS compositional analysis, the cubic particles had more Na content while the spherical ones had higher Zr content. It is concluded that growth mechanism of NaCl particles is different from that of zirconia particles. Drying of the former even at high temperatures leads to the formation of solid, fully‐filled, porous particles, whereas hollow, disrupted particles are formed using the latter. 相似文献
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XRD and XPS analyses revealed that a Fe(NO3)3·9H2O layer formed outside γ-Fe2O3 particles when Fe3O4 nanoparticles were treated with ferric nitrate. The particle density differed for untreated and treated particles and was not uniform for the latter. The specific saturation magnetization of both treated and untreated particles was used to estimate the thickness of the Fe(NO3)3·9H2O layer and the average density of the treated particles. The density of the treated particles was used to calculate the density of ferrofluids of different particle volume fractions. These values are in agreement with measured results. Therefore, the particle volume fraction can be designed to synthesize acid ionic ferrofluids based on Fe3O4 nanoparticles using Massart's method. 相似文献
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L. N. Korotkov T. N. Korotkova 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(10):1395-1398
The dielectric and polarization properties of potassium dihydrogen phosphate (KDP) single crystals doped with Li, Na, and NH4 impurities have been investigated in the temperature range 70–150 K. It is found that the domain freezing temperature in the lithium-containing sample exceeds that for nominally pure KDP. Disappearance of freezing is observed in the ammonium-doped crystal. 相似文献
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Liwang Ye Zhengdong Li Genbo Su Xinxin Zhuang Guozong Zheng 《Optics Communications》2007,275(2):399-403
KDP crystals were grown at growth rates from 5.0 to 19.0 mm/d. Transmittance, laser damage threshold and light scatter were detected. It has been shown that laser damage thresholds of KDP crystals decrease with the increase of the absorption coefficients. Large-scale impurity is an important factor that causes light absorption in UV range and reduces the damage threshold. 相似文献